JP2005291990A - Rail classification discriminating apparatus and rail classification discriminating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rail classification discriminating apparatus and a rail classification discriminating method for easily discriminating the classification of a rail, without being affected by a signal current flowing through the rail. <P>SOLUTION: When an AC magnetic field is applied to the rail to generate a demagnetizing field by an eddy current in the rail, change in the applied AC magnetic field and the demagnetizing field generated in the rail is detected as a change in an induced voltage; and the phase difference in the induced voltage by the detected AC magnetic field and the demagnetizing field is measured; the frequency of the AC magnetic field applied to the rail is adjusted so that the difference between the frequency of the eddy current and that of the signal current is equal to or larger than the prescribed value, to avoid interference between the eddy current and a signal current flowing through the rail. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rail type determination device and a rail type determination method.

  Currently, the main rails used for railways are ordinary rails (JIS E 1101) that have not been heat-treated due to differences in heat treatment (quenching), and heat treatment that has been heat-treated across the entire cross section of the head of ordinary rails. Rails (Head hardened rails: JIS E 1120) and end hardened rails (End Hardened Rails: JIS E 1123), where only the end heads of ordinary rails are heat-treated, can be broadly classified. Detailed regulations are defined in Japanese Industrial Standards (JIS).

  When laying on the rails described above, the bond wire for passing the current for the electric motor of the train is welded by a welding method such as the copper thermite method. In order to prevent the occurrence of cracks due to the tensile residual stress, a peening process is required in which a compressive stress is applied by hitting the periphery of the weld with a metal hammer or the like. However, there are not a few types of rails that have already been laid such that the type cannot be determined. In such a case, the peening process is performed on all rails. Since this work is often performed at midnight after the last train, there is a problem that noise to neighboring residents becomes a problem and wasteful man-hours are required. Therefore, there is an urgent need to make the rail type distinguishable on site.

By the way, in general, the rails before laying are applied with paints for identifying the rail type in different colors, and the rail type is determined based on the paint color. Also proposed is a method for measuring eddy currents generated in electrical conductors by electromagnetic coils, etc., and measuring the transformation rate in the electrical and magnetic properties generated by heat treatment in metal plates such as copper plates based on the measured values. (For example, refer to Patent Document 1).
JP-A-5-126798

  However, the method of determining the rail type on the basis of the paint color is that the paint on the rails of trains that have already been laid and used are often peeled off due to environmental conditions such as wind and snow over a long period of time. It is difficult to distinguish.

  In order to eliminate such inconvenience, it is conceivable to apply the method of Patent Document 1 for the determination of the rail type. However, the amount of carbon or nonmetal contained in the rail differs depending on the manufacturer, Because the characteristics of the rail conductivity change depending on the rail temperature, etc., the characteristics of the eddy current generated in the rail are not always constant, and it is necessary to correct for various conditions. There is a possibility.

  On the other hand, when the type of rail already laid is determined at the site, the return current that returns the current supplied from the train line to the substation, the train detection rail current for train detection, and the motor Since a signal current such as a current flows, the method of Patent Document 1 generates a beat that hinders measurement due to interference between the signal current and the induced current by the electromagnetic coil, and normal observation cannot be performed. .

  An object of the present invention is to provide a rail type discriminating apparatus and a rail type discriminating method capable of easily discriminating the rail type without being affected by the signal current flowing through the rail.

In order to solve the above-mentioned problem, the invention described in claim 1
Magnetic field generating means for applying an alternating magnetic field to the rail;
A magnetic field detecting means for detecting a change in a demagnetizing field caused by an eddy current generated in the rail in response to the alternating magnetic field and the alternating magnetic field as a change in induced voltage;
Measuring means for measuring the phase difference of the induced voltage due to the detected alternating magnetic field and demagnetizing field;
Adjusting means for adjusting the frequency of the alternating magnetic field;
It is characterized by having.

Moreover, in order to solve the said subject, invention of Claim 2 is the following.
Applying an alternating magnetic field to the rail;
Detecting a change in the demagnetizing field due to the eddy current generated in the rail in response to the alternating magnetic field and the alternating magnetic field, as a change in induced voltage;
Measuring the phase difference of the induced voltage due to the detected alternating magnetic field and demagnetizing field;
Adjusting the frequency of the alternating magnetic field based on the measured value;
It is characterized by including.

The invention according to claim 3 is the invention according to claim 2,
It is characterized in that measurement is performed at at least three or more different positions on the classification target rail, and the type of the rail is determined by comparing values obtained by this measurement.

The invention according to claim 4 is the invention according to claim 2,
The position where the measurement is performed includes a head of a rail end of the type identification target rail, a low portion of the rail, and a head of the center of the rail.

  According to the first aspect of the present invention, the magnetic field generating means for applying an alternating magnetic field to the rail, and the change in the demagnetizing field caused by the eddy current generated in the rail by receiving the alternating magnetic field and the alternating magnetic field by the magnetic generating means Magnetic field detecting means for detecting changes, measuring means for measuring the phase difference of the induced voltage due to the detected alternating magnetic field and demagnetizing field, and adjusting means for adjusting the frequency of the alternating magnetic field generated by the magnetic field generating means Therefore, even if the signal current flowing through the rail interferes with the eddy current generated by the application of the alternating magnetic field, the frequency of the alternating magnetic field can be adjusted by the adjusting means. The frequency difference from the current can be adjusted to be within a predetermined range. This makes it possible to measure the phase difference between the induced voltages due to the alternating magnetic field and the demagnetizing field without being affected by the signal current flowing through the rail. In addition, since the demagnetizing field generated in the rail by application of an alternating magnetic field changes in correlation with the composition of metal used in the rail and heat treatment, the rail type can be easily determined using this.

  According to the second aspect of the present invention, an alternating magnetic field is applied to the rail to generate a demagnetizing field due to the eddy current to the rail, and the applied alternating magnetic field and the change of the demagnetizing field generated in the rail are changed in the induced voltage. The phase difference of the induced voltage due to the detected alternating magnetic field and demagnetizing field is measured, and the frequency of the alternating magnetic field is adjusted based on the measured value, so that the signal current flowing in the rail is Even in the case where eddy currents generated by application of an alternating magnetic field interfere with each other, the frequency difference between the signal current and the eddy current can be adjusted based on the measured value so as to be a predetermined range or more. This makes it possible to measure the phase difference between the induced voltages due to the alternating magnetic field and the demagnetizing field without being affected by the signal current flowing through the rail. In addition, the demagnetizing field generated in the rail by applying an alternating magnetic field changes in correlation with the composition of metal used in the rail and the heat treatment, so that the rail type can be easily determined using this.

  According to the invention described in claim 3, the type of the rail is determined by performing measurement at at least three or more different positions of the type determination target rail and comparing the values obtained by this measurement. Depending on the type of rail, characteristics such as conductivity may be the same or different due to heat treatment performed by parts in the same rail, so the measurement results at at least three different parts are relatively compared. This makes it possible to easily determine the type of rail.

  According to the invention described in claim 4, the position where the measurement is performed usually includes at least the head of the rail end of the type determination target rail, the lower portion of the rail end, and the head of the center of the rail. Rails, heat treated rails and end heat treated rails can be easily identified.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. Note that the scope of the invention is not limited to this embodiment.

FIG. 1 is a schematic diagram showing a basic operation principle of a rail type discrimination device 1 according to the present invention.
As shown in FIG. 1, the rail type discriminating apparatus 1 includes an AC magnetic field generating circuit 10 as a magnetic field generating means for generating an AC magnetic field, an AC magnetic field generated from the AC magnetic field generating circuit 10, and this AC magnetic field As a magnetic field detection circuit 20 as a magnetic field detection means for detecting a demagnetizing field of eddy current generated in the rail by being applied to the rail, and as a measuring means for measuring the phase difference of the detected AC magnetic field and the induced voltage due to the demagnetizing field The measuring instrument 30 is configured.

  The AC magnetic field generation circuit 10 includes a coil 11 and a variable AC power source 12 as an adjusting unit capable of changing the frequency of an AC current flowing through the coil 11. The AC magnetic field generation circuit 10 has a function of generating an AC magnetic field by causing an AC current to flow from the variable AC power source 12 to the coil 11, and by bringing the AC magnetic field closer to a conductive rail, an eddy current is generated in the rail. Is generated.

  The magnetic field detection circuit 20 includes a coil 21 and a signal processing circuit 22, and counters the eddy current generated in the rail by the application of the alternating magnetic field generated by the alternating magnetic field generation circuit 10 and the alternating magnetic field by the alternating magnetic field generation circuit 10. A magnetic field is detected, the phase difference of the induced voltage due to the detected alternating magnetic field and demagnetizing field is extracted by a PLL circuit (not shown) included in the signal processing circuit 22, and the extracted phase difference is used as a measurement value in the measuring device 30. Output. The signal processing circuit 22 has an integration circuit 22a, and the integration circuit 22a performs beat compression described later.

  The measuring device 30 displays the phase difference of the induced voltage due to the alternating magnetic field and the demagnetizing field output from the magnetic field detection circuit 20 on a meter, a display device, or the like.

  Here, since the demagnetizing field of the eddy current generated in the rail by the application of the alternating magnetic field is affected by the composition of the metal used in the rail and the heat treatment, the difference is discriminated when the demagnetizing flux is detected by the magnetic field detection circuit 20. can do.

  Currently, three types of rails are mainly used: normal rails that have not been heat-treated, heat-treated rails that have been heat-treated across the entire cross section of the head of normal rails, and heat treatment only on the end heads of normal rails Can be broadly divided into end heat-treated rails that have been subjected to.

  With reference to FIG. 2, the heat treatment applied to the end heat treatment rail will be described. 2 (a) and 2 (b) respectively show a cross-sectional view and a vertical cross-sectional view of the head of the end heat treatment rail, and the hatched portion shows a portion to be heat treated. In addition, the site | part to which the heat processing shown here was standardized by JIS (End Hardened Rails: JIS E 1123), and the unit of the numerical value shown in the figure is mm.

  As shown to Fig.2 (a), it heat-processed to the depth of 15-30 mm from the rail top part of an edge part heat processing rail, and the depth of 10 mm from the head surface. Also, the heat treatment at the depth shown in FIG. 2A is within a range of 170 mm from the rail end (steady effect part 100 ± 10, decreasing part 40 or less, softening part 20 or less) as shown in FIG. 2B. It has been subjected.

  Therefore, as shown in FIG. 3, the head of the rail end (a in the figure; hereinafter referred to as the rail end head), the lower part of the rail (b in the figure; hereinafter referred to as the rail bottom), and a distance of 170 mm or more from the rail end. The magnetic field detection circuit 20 and the measuring device 30 generate demagnetizing fields generated by application of an alternating magnetic field by the alternating magnetic field generating circuit 10 at three positions in the center of the rail (c in the figure; hereinafter referred to as rail central head). It is possible to determine the type of rail by measuring and relatively comparing the obtained measurement values.

  If it demonstrates concretely, since heat processing is not performed in a normal rail, all the measured values in the above-mentioned three places become the same value. In the end heat-treated rail, the rail end head is heat-treated over a range of 170 mm from the rail end as described above, so only the rail end head of the above-mentioned three locations is measured at the other two locations. The value is different from the value. Moreover, in the heat-treated rail, since the heat treatment is applied to the entire rail head, only the rail lower portion of the above-described three places has a value different from the measured values of the other two places.

  From this, as shown in Table 1, by measuring the demagnetizing field at the rail end top, rail bottom, and rail center top of the rail and comparing the measured values relatively, the normal rail, end heat treated rail The three types of heat treatment rails can be discriminated. Table 1 shows whether there is a difference in the measured value when compared with the other two locations with the rail center head as a reference. A case where there is no difference in the measured value is indicated by a circle. This is indicated by a cross.

  In addition, although the position measured by the rail classification | category discrimination | determination apparatus 1 was made into the rail end head, a rail bottom part, and a rail center top, it is not restricted to this, Other positions may be sufficient. Moreover, although the location measured by the rail classification | category discriminating apparatus 1 was made into three places, it is not restricted to this, Four or more places may be sufficient and two places or less may be sufficient. In addition, since the metal composition of the top of the head may change due to the weight or wear of the train, when measuring the rail head, the head side is not measured. It is preferable to measure in parts.

  As described above, the normal rail, the heat-treated rail, and the end heat-treated rail can be identified by setting the position for measuring the rail to be classified as the rail end head, the rail lower portion, and the rail central head. it can.

  In addition, on the rails that have already been laid, there are signal currents such as the return current that sends the current supplied from the train line back to the substation, the train detection rail current for train detection, the current for the motor, etc. This signal current and the eddy current generated when the AC magnetic field generating circuit 10 applies an AC magnetic field to the rail interfere with each other, and a beat that disturbs measurement may occur. Therefore, by adjusting the frequency of the variable AC power supply 12 of the AC magnetic field generation circuit 10, the influence of the beat phenomenon is reduced by separating the two interfering frequencies.

Hereinafter, the beat reduction process will be described.
FIG. 4 is a diagram for explaining a beat generated by interference between a signal current flowing in the rail and an eddy current generated in the rail. Here, it is assumed that the frequency of the signal current is f1, and the frequency of the eddy current generated in the rail by electromagnetic induction is f2 (where f1 ≠ f2). For simplification of explanation, the amplitudes of the two currents are assumed to be equal.

  In the figure, W1 represents a waveform synthesized by interference between the waveform of the signal current frequency f1 and the waveform of the eddy current frequency f2, and as shown in the figure, the amplitude periodically becomes a waveform that repeatedly increases and decreases. As the amplitude changes, a beat is generated and its waveform is indicated by W2. Here, the beat frequency is | f1-f2 |.

  The beat frequency ranges from several Hz to several hundred Hz from the relationship between the frequency of the signal current flowing through the rail and the AC current output from the variable AC power supply 12 of the AC magnetic field generation circuit 10, but the rail has various frequencies. Since current is flowing, it is difficult to set the beat frequency to 100 Hz or higher if the frequency of the alternating current for generating eddy current in the rail is fixed. When the beat frequency is about 100 Hz or less, the measurement value obtained by the measuring instrument 30 changes with the beat frequency, so that an effective value cannot be read.

  On the other hand, the rail type discriminating apparatus 1 has an integration circuit 22a as shown in FIG. 1 in the signal processing circuit 22 and can compress the beat to some extent, but depending on the place where the rail is laid. The beat may be 1 Hz or less, and if a time constant sufficient to compress it is selected, the time constant will be several hundred seconds, so it takes too much time to measure and it is not practical.

  Thus, by increasing the difference between the two interfering frequencies by adjusting the frequency of the variable AC power supply 12, it is possible to obtain a time constant that is practical for compression in the integrating circuit 22a. Effective measurements can be obtained. Here, the adjustment of the frequency of the variable AC power source 12 may further include a circuit for determining the degree of fluctuation of the measurement value, and the adjustment may be automatically performed based on the determination result, or may be output to the measuring device 30. Manual adjustment may be made according to the fluctuation of the measured value. The frequency difference is preferably 200 Hz or more.

  Note that even if the frequency of the variable AC power supply 12 is adjusted so that the beat can be compressed and the measurement is possible (a valid measurement value can be read), the beat is generated, but the same rail If it is the same part, the same measured value is always obtained. Therefore, since the method for determining the rail type in the present invention is performed by relatively comparing the measured value in a specific part of the rail with the measured value in the other part, the measurement value itself has exceptional strictness. It is possible to determine the type of rail as long as an effective measurement value can be read.

  As described above, an AC magnetic field is applied to the rail to generate a demagnetizing field due to the eddy current in the rail, and the applied AC magnetic field and the change in the demagnetizing field generated in the rail are detected as a change in induced voltage. When measuring the phase difference of the induced voltage due to the detected alternating magnetic field and demagnetizing field, the frequency difference between the eddy current and the signal current is used to avoid interference between the eddy current generated in the rail and the signal current flowing in the rail. By adjusting the frequency of the variable AC power supply 12 so as to be equal to or greater than a predetermined value, the phase difference of the induced voltage due to the AC magnetic field and the demagnetizing field is measured without being affected by the signal current flowing through the rail. The type of rail can be easily determined by relatively comparing the measurement values obtained in this way.

  The detailed configuration and detailed operation of the rail type determination device 1 in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

It is a block diagram which shows an example of the basic form of a rail classification discrimination device. It is a figure which shows the range to which the heat processing of the edge part heat processing rail was performed. It is a figure explaining the measurement position of the rail by a rail classification discrimination device. It is a figure for demonstrating the beat which generate | occur | produces by interference with the signal current which flows into a rail, and the eddy current which generate | occur | produces in a rail.

Explanation of symbols

1 Rail Type Discriminating Device 10 AC Magnetic Field Generation Circuit 11 Coil 12 Variable AC Power Supply 20 Magnetic Field Detection Circuit 21 Coil 22 Signal Processing Circuit 22a Integration Circuit 30 Measuring Instrument

Claims (4)

Magnetic field generating means for applying an alternating magnetic field to the rail;
A magnetic field detecting means for detecting a change in a demagnetizing field caused by an eddy current generated in the rail in response to the alternating magnetic field and the alternating magnetic field as a change in induced voltage;
Measuring means for measuring the phase difference of the induced voltage due to the detected alternating magnetic field and demagnetizing field;
Adjusting means for adjusting the frequency of the alternating magnetic field;
A rail type discrimination device comprising: Applying an alternating magnetic field to the rail;
Detecting a change in the demagnetizing field due to the eddy current generated in the rail in response to the alternating magnetic field and the alternating magnetic field, as a change in induced voltage;
Measuring the phase difference of the induced voltage due to the detected alternating magnetic field and demagnetizing field;
Adjusting the frequency of the alternating magnetic field based on the measured value;
A rail type discrimination method comprising:   The rail type discrimination according to claim 2, wherein the type of the rail is discriminated by performing measurement at at least three different positions of the type discrimination target rail and comparing values obtained by the measurement. Method.   The rail type determination method according to claim 3, wherein the position where the measurement is performed includes a head of a rail end of the classification determination target rail, a low part of the rail, and a head of the center of the rail.

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